Optimal dynamic current control for externally excited synchronous machines

Control of externally excited synchronous machine involves specifying current setpoints with respect to system limits such as maximum phase and excitation currents as well as the inverter voltages, while also achieving the desired torque in an energy-efficient manner. However, this is often only achievable in stationary operation. To attain the desired torque in dynamic scenarios, a nonlinear input-output linearization method paired with an asymptotic tracking controller for current control is utilized. Additionally, the tracking controller is extended to accommodate for voltage constraints. Optimal dynamic current setpoints are determined by solving a nonlinear optimization problem in a combinatorial manner in order to allow for a real-time execution of the algorithm. Simulations and comparisons with a standard FOC approach demonstrate the algorithm’s effectiveness in achieving the desired torque, minimizing losses, complying with system constraints, and maintaining a low computational load.